Biotech stocks are outperforming today, on the heels of some major M&A headlineswithin the sector. Among the drugmakers heading higher on sector tailwinds is Gilead Sciences, Inc. (NASDAQ:GILD) -- which is up 3.2% at $81.54, and in the crosshairs of options traders.

Diving right in, GILD call options are changing hands at two times the usual intraday rate. The most active strike is the October 82.50 call, where traders may be buying new out-of-the-money positions, hoping the underlying stock will topple $82.50 by the close on Friday, Oct. 21 -- when the newly front-month options expire. Meanwhile, even shorter-term bulls are buying to open the weekly 9/23 82-strike call, targeting additional end-of-week upside for GILD.

Today's call buying merely echoes the prevailing trend in the stock's options pits. At the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), traders have bought to open triple the number of calls as puts in the past two weeks. The resultant call/put volume ratio of 3.13 ranks only 12 percentage points from a 12-month peak.

Further underscoring GILD's call-skew is its Schaeffer's put/call open interest ratio (SOIR) of 0.45, with calls more than doubling puts among options expiring in the next three months. Of note, this SOIR rests only 5 percentage points from an annual low.

Now appears to be a great time to purchase premium on short-term Gilead options. The stock's Schaeffer's Volatility Index (SVI) of 21% outstrips only 4% of readings from the prior year. Additionally, GILD's 30-day at-the-money implied volatility of 21.8% rests in the bottom 8% of all readings from the last 12 months.